1. Field of the Invention
The invention relates to a coordinated system of vehicular and pedestrian traffic flow and traffic light controls.
2. Description of the Related Art
A conventional roadway intersection has two streets, generally perpendicular to one another, with vehicular traffic capable of flowing in both directions on each of the streets. Traffic signals control the movement of the vehicles. In cities, sidewalks are provided for pedestrians to safely move about. They, too, are often directed by traffic signals. Conventionally, these signals are of the "Walk"/"Don't Walk" type which are synchronized with the vehicle traffic signals.
Considering a network of streets as allowing vehicular traffic to travel in the North and South directions, intersecting streets would then allow vehicles to travel in the East and West directions. In the New York City midtown area, for example, wide avenues carry vehicles North and South, while intersecting narrow streets carry traffic East and West. Currently, a backing up or impedance to smooth and continuous vehicular traffic occurs when a vehicle traveling on an avenue in a northerly direction, for example, seeks to make a right or left turn onto the intersecting street to travel easterly or westerly. More specifically, the vehicle seeking to turn off in a northerly direction must wait until the pedestrians cross the intersecting street and clear the crosswalk, prior to making the right-hand or left-hand turn onto the intersecting street. In busy cities, especially during lunch hours and pleasant weather days, only a few cars can transfer from an avenue to the intersecting street as a result of the large number of pedestrians impeding such movement. Similarly, if a car traveling in the northerly direction on an avenue, for example, decides to travel on the intersecting street in a westerly direction, i.e., make a left turn onto the connecting street, the car must also wait in the middle of the intersection until the oncoming cars traveling in the southerly direction on the same street clear the intersection. Next, after being sure that it is safe to cross in front of the oncoming southerly traffic, the vehicle must also be sure that the crosswalk connecting passengers from the southwest and northwest corners is clear of pedestrians, prior to the car turning and then increasing speed on the westerly directed street.
This waiting has a negative impact on the smooth flow of vehicular traffic and can, on peak hours, easily result in gridlock and driver frustration.
Gridlock is a common problem confronting crowded city streets and generally can occur when an intersection becomes blocked by either vehicles desiring to make left-hand turns from streets carrying traffic in two directions (compounded by the necessity of waiting for pedestrians to clear the crosswalks) or by vehicles making either right or left-hand turns from one-way streets, since they must also wait for pedestrian clearance of the crosswalks. The Jul. 17, 1988 issue of the New York Times, published on page E7 an article relating to gridlock and its tremendous negative impact on metropolitan streets and quality of life for city dwellers.
In addition, vehicular traffic is forced to make frequent stops at traffic lights on most city streets to permit crossing movements for vehicular and pedestrian traffic at street intersections. This leads to aggravating delays in travel time and undesired energy consumption.
My U.S. Pat. No. 4,927,288 issued May 22, 1990, offers a simple and efficient means for eliminating the possibility of vehicle gridlock by providing for better traffic flow on existing street networks. The '288 patent discloses a road traffic network, also referred to as the Multiple Loop System (MLS), wherein the fundamental building block is an endless loop of one way traffic flow completely surrounded by the first endless loop and having traffic flow opposite in direction to the traffic flow direction of the first loop with an interconnecting traffic flow roadway between the loops.
Although the '288 patent is effective in providing for a smooth and continuous flow of vehicular traffic on existing roadways, it is not directed to facilitating pedestrian flow nor is there any discussion or solution to the problem of intermodal conflict or friction. Intermodal conflict, as used herein, refers to the slowing of vehicle traffic flow due to a need to avoid accidents or injury involving either two or more vehicular streams of traffic, or a vehicle and a pedestrian stream of traffic at street intersections.
My other already issued patent, U.S. Pat. No. 5,092,705 issued Mar. 3, 1992, relates to a method and system for controlling vehicular and pedestrian traffic at intersections of the Multiple Loop System type disclosed in my '288 patent. In brief summary, the '705 patent relates to a method for controlling the vehicular traffic light signals at intersections of avenues and crosswalks, along with "Walk"/"Don't Walk" traffic signals for pedestrians at the crosswalks, so that the Multiple Loop System operates to its maximum efficiency, all while preserving safety and reducing intermodal conflicts.
Another patent that has relevance to the Multiple Loop System disclosed in my '288 patent is my U.S. Pat. No. 5,330,278 issued Jul. 19, 1994. This patent teaches a method for coordinating traffic signals on a roadway network, preferably of the Multiple Loop System type. Here, two phase traffic signals, red and green, of equal duration are employed at the roadway intersections in such a manner that idling time is minimized while vehicular traffic flow is maximized, all with reduced intermodal conflicts.
Even though the '278 patent is effective at minimizing idling time while maximizing traffic flow, the preferred embodiment of the '278 invention is its application with the Multiple Loop System disclosed in my '288 patent. An inherent disadvantage of the Multiple Loop System is that it does not allow traffic to cross intersections along either axis nor does it accommodate left turns across oncoming traffic due to the one-way looping network configurations. Thus, the '288 patent and its supporting elements in both the '705 and '278 patents provide an efficient road traffic network system only within the context of the Multiple Loop System.
Preferably, a traffic signal system that increases the flow of vehicular traffic on city streets and avenues while minimizing idling time and intermodal conflicts is desired without the need to utilize the Multiple Loop System. Such a system would allow traffic to cross intersections along either axis and to accommodate left-hand turns in special circumstances across oncoming traffic. Implementation of the ideal system onto existing roadways with minimum modifications provides less disruptive service for drivers and allows city planners to make maximum use of the existing roadways. Thus, a traffic network signalization system utilizing existing roadway conditions requiring minimum modifications while allowing traffic to cross along either axis and to accommodate left-hand turns in special circumstances across oncoming traffic is not disclosed in prior art.